Heat two tablespoons olive oil in a non-stick skillet over high heat.,______,Turn tuna over and continue cooking, about two minutes for rare, four for medium.,Transfer tuna to plate and keep warm.,Add remaining olive oil, onions, cilantro, ginger and garlic to same skillet and saute about 30 seconds.,Mix in mushrooms and soy sauce and simmer 30 seconds for shiitake, 1 minute for morels.,Add half and half and simmer until thickened, about 3-4 minutes.,Stir in lemon juice.,Spoon sauce onto plates and place tuna steak on top.,Rice goes well.